Scientists have observed a significant number of coral reefs showing signs of bleaching due to heat stress, a troubling sign for the health of the world’s oceans.
According to the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch, 54% of the Earth’s oceans now experience heat stress high enough to cause coral bleaching.
In an announcement confirming the global coral bleaching event, the NOAA commented on the frequency of such events.
“The world is currently experiencing a global coral bleaching event, according to NOAA scientists. This is the fourth global event on record and the second in the last 10 years,” the announcement said.
Dr. Derek Manzello, the director of Coral Reef Watch, told The Guardian that this current event is on track to beat the previous record for the most widespread bleaching event.
“The percentage of reef areas experiencing bleaching-level heat stress has been increasing by roughly 1% per week,” Manzello said.
According to the NOAA, mass bleaching of coral reefs has been confirmed in Florida, the Caribbean, Brazil, the Middle East, east Africa, several countries in the South Pacific, and several places in the Indian Ocean.
Coral bleaching is the process by which colorful fields of coral that dot the oceans lose their color and turn completely white. The colors people observe in coral are due to microscopic algae that form a symbiotic relationship with the coral, ensuring they both survive.
When coral undergoes heat stress, it expels the algae and loses its vibrant color. If temperatures remain high, the coral will die without its algae companions.
This can be a huge issue for the environment in the world’s oceans because once a coral reef dies, it often never comes back. These massive reefs support humans and the local wildlife.
Coral reefs help protect coastlines from storms and erosion. They are also a source of food, medicine, and income for humans. The NOAA estimates that over half a billion people around the world depend on coral reefs for “food, income, and protection.”
Nearly one-quarter of all marine animal species in the oceans depend on the habitat provided by coral reefs, which cover less than 1% of the world’s oceans.
Scientists have been predicting that coral bleaching events would continue to get worse in recent years.
“Climate model predictions for coral reefs have been suggesting for years that bleaching impacts would increase in frequency and magnitude as the ocean warms,” said Jennifer Koss, director of NOAA’s Coral Reef Conservation Program (CRCP).
Researchers assert that the leading cause of coral bleaching is the rise in average global surface temperatures as a result of global warming.
“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severe,” Manzello said. “When these events are sufficiently severe or prolonged, they can cause coral mortality, which hurts the people who depend on the coral reefs for their livelihoods.”
The first confirmed mass coral bleaching event occurred in 1998. This recent incident is the fourth planet-wide coral bleaching event confirmed since that time.
Scientists define that a “global bleaching event” occurs when at least 12% of corals in the Pacific, Atlantic, and Indian oceans have confirmed reports of mass bleaching.
